Best way to detect a bot

[EricH]

Originally Posted by dpeterson3

First off, someone told me last year that IR, Ultrasonic, and radio sensors were illegal because they emit waves (first year for me, so I believed him).

You don't now, right?

Though we'll find out what sensors are (not) legal for 2009 in a very few days...

[Bryan Herbst]

Although it is not possible this year (and thus moderately unhelpful to you right now), the new control system has the capability for robot-to-robot communication.

So, you could get data from another robot (say GPS data, for example), and use that to navigate around the other robot. If you were really clever and had excellent programmers, you could also program in a sort of a map of the field too, and map out robots, obstacles, and such to make your autonomous mode even more robust and adaptable.

However, for the time being, you are pretty much stuck with IR, Ultrasonic, and Touch.

Someone mentioned sound- I personally don't think that this is a terribly great idea, as competitions tend to be quite noisy, and you would be picking up a lot of background noise, not to mention your own robots' noise.
One way you COULD make this work would be to detect very high frequencies (outside of any range you would get inside the field at the competition), and have two pre-made frequency emitters to give to your allies. However, I can't recall the legality of noise emitters at competitions, so make sure to check first.

EDIT: Something else I just thought of that would definitely not work in FIRST, but would be pretty cool- Dark Knight style "seeing" via cell phones, and mapping out where your bot is

[gblake]

Folks,

Shielding sensors/antennae from ambient signals created by your own bot is possible.

Determining a constellation of bot signature characteristics that most FIRST bots are likely to exhibit is possible.

Detecting robot generated noise (em or acoustic) within the ambient noise of an arena is possible.

Using vision systems to track multiple moving objects and estimate which are the nearby robots is possible.

Computing estimates of these signals' sources' trajectories is possible.

Satellite receivers, deep space probe receivers, sonars and radars, FM radios, ham radios etc. all extract weak signals from relatively harsh noise fields. Some of these also estimate directions and ranges to the sources.

Doing these things on a FIRST bot is possible.

So, if you are really motivated - I say go for it. But you (and a friend or two you infect with your enthusiasm) really, really need to be motivated.

My hunch is that during this build season you would have enough time to do research that would give you a sense of how big the project will need to be ($ and labor hours), and to do some very simple proof-of-concept tests on one or two candidate sensors and computing platforms. Maybe you would stick some parts on this season's bot to collect real world data.

Between now and next season you could probably develop something that would work well enough to be proud of it. Then you build a copy, equip the 2010 bot with it, publish results, and enjoy seeing the system work on the field.

Regardless of how well it works, you also get to enjoy telling the judges, other teams, and employers/schools about the mountains of math, software, and cross-disciplinary systems engineering you, your team covered along the way (students and mentors (you might need to connect with a specialist or two for this project)). You all will have exactly accomplished more than one of FIRST's primary objectives.

This project is do-able, but it is not a "quicky" if you start from scratch. However, paying the price of success in honest effort, and being able to plan and guide a non-trivial project from start to finish are both very valuable skills to learn and practice using.

Again, if you are serious and motivated for the long haul, then I say "Go for it!" You eat an elephant one bite at a time. This is a hippo. Eating it will take you several "bites", but it can be eaten.

Blake
PS: I'll bet that I can connect you with some signal processing experts (filtering out noise, sampling correctly, detecting correlated signals, estimating ranges and bearings) and some guidance-and-control experts (deciding how to autonomously use the sensor/processor outputs to decide how to drive your bot toward a goal) if you can't tap into an existing network of mentors here on CD or in your team's circle of contacts.

[DonRotolo]

Originally Posted by Daniel_LaFleur

put a Faraday (sp?) cage around your motors which would affect their efficiency.

I'm not sure how a faraday cage will affect a motors efficiency - that's a new one for me. Can you help me understand?

Originally Posted by Qbranch

until the sensors caught fire at the Midwest regional.

Um...caught fire?
[quote=gblake;789324]Doing these things on a FIRST bot is possible.]/QUOTE]
Indeed it is. It is ambitious, but absolutely possible, and by that I mean some motivated high school students could get it done.

Here's the challenge: You are being given a very, very generous offer of assistance in making this a reality. I don't want to mislead you: This is not a project for this build season. But do it, and that'll look absolutely stunning on your college application, in the newspaper, etc. Not to mention on Einstein.


That being said, often we look to nature to solve problems. How would nature solve this one? That is, how would YOU (a human) detect a robot? I would do it visually...but what if you were blind? Think on that for a while, maybe some solutions will come to mind...


Don

[Daniel_LaFleur]

Originally Posted by Don Rotolo

I'm not sure how a faraday cage will affect a motors efficiency - that's a new one for me. Can you help me understand?

To my understanding the closer a Faraday cage is to a motor, the more it interferes (disrupts?) with the EM field driving the motor (creating a return to ground through the faraday cage).

... or maybe I'm just misremembering my inductance field dynamics.

[dpeterson3]

Thanks. I know this is not a project for this season. I am chief electrical/chief programmer/team captian/mechanical designer (we only have about 10 students and 6 mentors, so everyone does everything). Check out this link though. It is quite doable in a short time and would really help.

www.pyroelectro.com/projects/ir_radar/index.html

I am thinking of using this ir radar to detect other bots and then the camera to zero in on the trailer and fire.

[Sparks333]

Hi all!
During the ring-playing game two years ago, our team used an array of ultrasonic sensors to detect not only the the base of the rack, but also the spider leg caps. They were the MaxBotix LV1's, and I just wanted to highlight a few of the issues with using such a system. As it was, the system (I built it at as an extra project) only really worked well in Las Vegas - helped us win the regional - but they were touchy little buggers.

The MaxBotix sensors are pretty well directional, which makes them ideal for FIRST sensors. They are also highly flexible and have an array of fun abilities that come in handy - serial communication, PWM outputs, analog outputs and chainable single-shot modes are common features. Maxbotix even has a few with different directionalities. That being said, there are a few challenges with Ultrasonic.

The first and foremost is the use of multiple sensors. If they are all on the same frequency (MaxBotix uses 40 khz) then signals coming from one can be interpreted as a return from another, causing garbage readings. The best way to fix this is to cycle through each sensor independently, so there is never more than one sensor going at once, but this takes a little more work than just a plug 'n play solution.

The other problem is what is called multipath. For a FIRST bot, the most predictable place to detect another 'bot is about 6" off the ground. Unfortunately, it is around this height that the ultrasonic signal begins to bounce off the floor, causing multiple return signals that usually result in inconsistent or dirty readings. This is solved by raising the sensor off the floor, or by averaging many values, but either way means that robot detection is rendered difficult.

In short, ultrasonic is a viable solution (and, in my opinion, better than IR) but it has a few significant drawbacks that must be addressed it is to be used in an effective manner.

Sparks

[gblake]

Originally Posted by dpeterson3

Thanks. I know this is not a project for this season. I am chief electrical/chief programmer/team captian/mechanical designer (we only have about 10 students and 6 mentors, so everyone does everything). Check out this link though. It is quite doable in a short time and would really help.

www.pyroelectro.com/projects/ir_radar/index.html

I am thinking of using this ir radar to detect other bots and then the camera to zero in on the trailer and fire.

Have fun!

[DonRotolo]

Originally Posted by Daniel_LaFleur

To my understanding the closer a Faraday cage is to a motor, the more it interferes (disrupts?) with the EM field driving the motor (creating a return to ground through the faraday cage).

... or maybe I'm just misremembering my inductance field dynamics.

No, my question was sincere and honest. My EM fields course remains a blur from the distant past.

Some effects upon the EM field outside the motor case seems reasonable to expect, and since it is part of the return path for the stuff happening inside the motor (although quite a bit less intense, considering the motor case is steel and some white metal and acts as a cage itself) it probably has some effect. Maybe someone can argue the magnitude of that effect, but now I see that there can be an effect.

Thanks.

.

[XXShadowXX]

Hint: (Compasses work in Faraday cages)